Single crystal silicon is the starting material in many processes for fabricating semiconductor electronic components. This silicon is commonly prepared in a crystal puller according to the Czochralski process. In this process, a single crystal silicon ingot is produced by melting polycrystalline silicon (i.e., polysilicon) in a crucible, dipping a seed crystal into the molten silicon, withdrawing the seed crystal in a manner sufficient to achieve the diameter desired for the ingot, and growing the ingot at that diameter.
After an ingot has been pulled from the molten silicon, some molten silicon may be left within the crucible in order to decrease the amount of time required to melt additional raw polysilicon subsequently charged into the crucible. A feed tool is also used during this subsequent charging to shield portions of the crystal puller from splatter caused when the raw polysilicon contacts the molten silicon.
During use, the feed tool is often subject to elevated temperatures compared to the temperatures at which it is stored when not in use. These changes in temperature result in the creation of thermal stresses within components of the feed tool. These stresses may in turn eventually cause the feed tool to deteriorate. Moreover, prior feed tools are often made from materials which deteriorate when contacted by silicon.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.